DataManager.java

package br.com.catbag.gifreduxsample.asyncs.data;

import android.content.Context;
import android.support.annotation.NonNull;
import android.util.Log;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.snappydb.SnappydbException;
import com.umaplay.fluxxan.util.ThreadUtils;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import br.com.catbag.gifreduxsample.asyncs.data.net.rest.retrofit.RetrofitBuilder;
import br.com.catbag.gifreduxsample.asyncs.data.net.rest.riffsy.api.RiffsyRoutes;
import br.com.catbag.gifreduxsample.asyncs.data.net.rest.riffsy.model.RiffsyMedia;
import br.com.catbag.gifreduxsample.asyncs.data.net.rest.riffsy.model.RiffsyResponse;
import br.com.catbag.gifreduxsample.asyncs.data.net.rest.riffsy.model.RiffsyResult;
import br.com.catbag.gifreduxsample.asyncs.data.storage.Database;
import br.com.catbag.gifreduxsample.models.AppState;
import br.com.catbag.gifreduxsample.models.Gif;
import br.com.catbag.gifreduxsample.models.ImmutableAppState;
import br.com.catbag.gifreduxsample.models.ImmutableGif;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

/**
 Copyright 26/10/2016
 Felipe Piñeiro (fpbitencourt@gmail.com),
 Nilton Vasques (nilton.vasques@gmail.com) and
 Raul Abreu (raulccabreu@gmail.com)

 Be free to ask for help, email us!

 Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 in compliance with the License. You may obtain a copy of the License at
 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software distributed under the License
 is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 implied. See the License for the specific language governing permissions and limitations under
 the License.
 **/

public class DataManager {
    private static Float sRiffsyNext = null;
    private final RiffsyRoutes mRiffsyRoutes;

    private Database mDatabase;
    private boolean mIsSavingAppState = false;
    private SaveAppStateRunnable mNextSaveAppStateRunnable;

    public DataManager(Context context) {
        mDatabase = new Database(context);
        mRiffsyRoutes = RetrofitBuilder.getInstance()
                .createApiEndpoint(RiffsyRoutes.class, RiffsyRoutes.BASE_URL);
    }

    public boolean isSavingAppState() {
        return mIsSavingAppState;
    }

    public void saveAppState(AppState appState) {
        mNextSaveAppStateRunnable = new DataManager.SaveAppStateRunnable(appState);
        executeSaveAppStateTask();
    }

    public void loadAppState(final LoadAppStateListener listener) {
        new Thread(() -> {
            try {
                listener.onLoaded(mDatabase.getAppState());
            } catch (SnappydbException | IOException e) {
                listener.onLoaded(getAppStateDefault());
                Log.e(getClass().getSimpleName(), "appstate not loaded", e);
            }
        }).start();
    }

    public void fetchGifs(final GifListLoadListener listener) {
        Call call = mRiffsyRoutes.getTrendingResults(RiffsyRoutes.DEFAULT_LIMIT_COUNT, sRiffsyNext);
        call.enqueue(new Callback<RiffsyResponse>() {
            @Override
            public void onResponse(Call<RiffsyResponse> call, Response<RiffsyResponse> response) {
                Map<String, Gif> gifs = extractGifsFromRiffsyResponse(response);

                sRiffsyNext = response.body().next();
                boolean hasMore = sRiffsyNext != null;
                listener.onLoaded(gifs, hasMore);
            }

            @Override
            public void onFailure(Call<RiffsyResponse> call, Throwable t) {
                Log.e(getClass().getSimpleName(), "onFailure", t);
            }
        });
    }

    private void executeSaveAppStateTask() {
        if (mNextSaveAppStateRunnable != null && !mIsSavingAppState) {
            mIsSavingAppState = true;
            ThreadUtils.runInBackground(mNextSaveAppStateRunnable);
            mNextSaveAppStateRunnable = null;
        }
    }

    private void onFinishedSaveAppStateTask() {
        ThreadUtils.runOnMain(() -> {
            mIsSavingAppState = false;
            executeSaveAppStateTask();
        });
    }

    @NonNull
    private Map<String, Gif> extractGifsFromRiffsyResponse(Response<RiffsyResponse> response) {
        List<RiffsyResult> results = response.body().results();
        Map<String, Gif> gifs = new LinkedHashMap<>();
        for (RiffsyResult result : results) {
            List<RiffsyMedia> riffsyMedias = result.media();
            if (riffsyMedias.size() > 0) {
                Gif gif = ImmutableGif.builder()
                        .url(riffsyMedias.get(0).gif().url())
                        .title(result.title())
                        .uuid(UUID.randomUUID().toString()).build();
                gifs.put(gif.getUuid(), gif);
            }
        }
        return gifs;
    }

    public static AppState getAppStateDefault() {
        String[] uuids = {"1", "2", "3", "4", "5" };
        String[] titles = {"Gif 1", "Gif 2", "Gif 3", "Gif 4", "Gif 5" };
        String[] urls = {
                "https://media.giphy.com/media/l0HlE56oAxpngfnWM/giphy.gif",
                "http://inspirandoideias.com.br/blog/wp-content/uploads/2015/03/"
                        + "b3368a682fc5ff891e41baad2731f4b6.gif",
                "https://media.giphy.com/media/9fbYYzdf6BbQA/giphy.gif",
                "https://media.giphy.com/media/l2YWl1oQlNvthGWrK/giphy.gif",
                "https://media.giphy.com/media/3oriNQHSU0bVcFW5sA/giphy.gif"
        };

        Map<String, Gif> gifs = new LinkedHashMap<>();
        for (int i = 0; i < titles.length; i++) {
            Gif gif = buildGif(uuids[i], titles[i], urls[i]);
            gifs.put(gif.getUuid(), gif);
        }

        return ImmutableAppState.builder().putAllGifs(gifs).build();
    }

    private static Gif buildGif(String uuid, String title, String url) {
        return ImmutableGif.builder().uuid(uuid).title(title).url(url).build();
    }

    public interface LoadAppStateListener {
        void onLoaded(AppState appState);
    }

    public interface GifListLoadListener {
        void onLoaded(Map<String, Gif> gifs, boolean hasMore);
    }

    private class SaveAppStateRunnable implements Runnable {

        private AppState mAppState;

        public SaveAppStateRunnable(AppState appState) {
            mAppState = appState;
        }

        @Override
        public void run() {
            try {
                mDatabase.saveAppState(mAppState);
            } catch (SnappydbException | JsonProcessingException e) {
                Log.e(getClass().getSimpleName(), "unsaved appstate", e);
            }
            onFinishedSaveAppStateTask();
        }

    }

}